(1) Field of the Invention
The instant invention relates to automotive battery jumper cables for connecting a weak battery to a stronger battery, and more particularly to a clamp for a jumper cable which reduces the chance of an electrical arc when making the connection.
(2) Description of the Prior Art
Automotive batteries produce both hydrogen and oxygen gas as a result of being charged and discharged. These gases can potentially be ignited, causing an explosion. One potential cause of ignition can be sparks due to electrical arcs that can occur when connecting jumper cables to the battery terminals. Essentially, jumper cables comprise two electrically conductive cables with spring clamps at each end of the cables to releasably engage the battery terminals. Typically, an arc, or sparking occurs directly at the battery terminal when connecting the last, i.e., fourth, clamp to the respective battery. To reduce the chance of such sparks igniting the gases around the battery, jumper cables having remote switching devices located well away from the battery terminals have heretofore been known in the art. In this regard, the U.S. Pat. No. to Asbury, 4,662,696 is representative of the prior art devices. The patent to Asbury discloses a battery jumper cable having a safety switch located intermediate the clamp ends of the cable. The switch is normally biased to the open position and includes a handle, which when depressed makes electrical contact between the leads of the battery cable.
The instant invention provides an automotive battery jumper cable including an improved clamp which eliminates the need for a manually activated remote safety switch. The instant jumper cable assembly comprises an electrically conductive cable which is terminated at each end by the improved clamp. Each of the clamps comprises a pair of gripping members each having a jaw end and a handle end. The gripping members are pivotably connected to each other about an axis between the jaw ends and the handle ends. A torsion spring is mounted on the gripping members for normally urging the jaw ends toward each other. Each of the jaw ends of the gripping member is provided with a copper jaw member for engaging and grasping the battery terminal. One of the jaws on each clamp is not connected to the cable. However, the other jaw of each clamp is electrically connected to the respective end of the cable via an encapsulated pressure switch. It is to be noted that only one of the four clamps needs to have the encapsulated pressure switch to prevent arcing. The pressure switch is physically positioned between the copper jaw and the jaw end of the gripping member such that spring pressure provided by the torsion spring is operative for closing the pressure switch when the clamp is mounted on a battery terminal. One contact of the switch is connected to the copper jaw and the other contact is connected to the cable. Both contacts are electrically insulated within the encapsulated switch. Since electrical connection is completed inside the encapsulated switch, any potential spark is insulated within the switch. An in-line fuse may also be positioned on the cable to provide short-circuit protection.
Accordingly, among the objects of the instant invention are: the provision of an improved clamp for an automotive battery jumper cable which reduces arcing in the vicinity of the battery terminal; the provision of a battery jumper cable assembly which is terminated at each end by the improved clamp of the invention; and the provision of a battery jumper cable assembly including the instant clamp members and further including an in-line fuse in the cable for preventing short circuits.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.